Magnetic heads having magnetic films that are more recessed than insulating films, and systems having such heads

ABSTRACT

A structure according to one embodiment includes a substrate having a media facing side; and a thin film stack formed on the substrate, the thin film stack including magnetic films and insulating films, wherein the thin film stack is recessed from a plane extending along the media facing side of the substrate, wherein the magnetic films are recessed more than the insulating films, wherein the magnetic films each have a substantially flat media facing surface, wherein the insulating films each have a substantially flat media facing surface.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/193,834 filed Aug. 19, 2008, and which is herein incorporated byreference.

BACKGROUND

The present invention relates to magnetic recording heads, and moreparticularly, this invention relates to magnetic heads.

In magnetic storage systems, data is read from and written onto magneticrecording media utilizing magnetic transducers commonly. Data is writtenon the magnetic recording media by moving a magnetic recordingtransducer to a position over the media where the data is to be stored.The magnetic recording transducer then generates a magnetic field, whichencodes the data into the magnetic media. Data is read from the media bysimilarly positioning the magnetic read transducer and then sensing themagnetic field of the magnetic media. Read and write operations may beindependently synchronized with the movement of the media to ensure thatthe data can be read from and written to the desired location on themedia.

An important and continuing goal in the data storage industry is that ofincreasing the density of data stored on a medium. For tape storagesystems, that goal has lead to increasing the track density on recordingtape, and decreasing the thickness of the magnetic tape medium. However,the development of small footprint, higher performance tape drivesystems has created various problems in the design of a tape headassembly for use in such systems.

In a tape drive system, magnetic tape is moved over the surface of thetape head at high speed. This movement generally entrains a film of airbetween the head and tape. Usually the tape head is designed forminimizing the spacing between the head and the tape. The spacingbetween the magnetic head and the magnetic tape is crucial so that therecording gaps of the write transducers, which are the source of themagnetic recording flux, ideally contact the tape to effect efficientsignal transfer, and so that the read elements ideally contact the tapeto provide effective coupling of the magnetic field from the tape to theread element.

One particular problem which may be encountered when tape is moved overthe surface of the tape recording head is the tape induced bridging ofmetallic portions of the thin films across the top portions of thefilms. As a result, thin films which are to be insulated from each othermay actually come into electrical contact with each other, which in timemay result in shorting and failure of the head. This effect can be seenin FIG. 2D, and will be explained in more detail later. Therefore, itwould be favorable to have a technique of selectively altering thesurface heights of thin films, allowing an insulator to have a highersurface height than surrounding poles or shields, to minimize thisbridging effect.

Additionally, the thin entire film region may be recessed from thesurrounding components, such as the substrate and closure, so that thetape will rarely come into contact with the head components in the thinfilm region. One method to recess the thin film region is plasmaetching, such as argon plasma etching. However, as is well known, anargon plasma etches nickel iron alloys and some other metals commonlyused in magnetic heads much more rapidly than the surroundinginsulators. Thus, while plasma etching may produce an overall recessionfor all materials in the gap, the amount of etching required to producethe desired overall recession may produce excessive magnetic pole,sensor, and shield recession, and thus lead to excessive spacing loss.

What is needed is a method to produce overall recession withoutexcessive metal recession.

SUMMARY

A structure according to one embodiment includes a substrate having amedia facing side; and a thin film stack formed on the substrate, thethin film stack including magnetic films and insulating films, whereinthe thin film stack is recessed from a plane extending along the mediafacing side of the substrate, wherein the magnetic films are recessedmore than the insulating films, wherein the magnetic films each have asubstantially flat media facing surface, wherein the insulating filmseach have a substantially flat media facing surface.

Any of these embodiments may be implemented in a magnetic data storagesystem such as a tape drive system, which may include a magnetic head asrecited above, a drive mechanism for passing a magnetic medium (e.g.,recording tape) over the magnetic head, and a controller electricallycoupled to the magnetic head.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic diagram of a simplified tape drive systemaccording to one embodiment.

FIG. 2 illustrates a side view of a flat-lapped, bi-directional,two-module magnetic tape head according to one embodiment.

FIG. 2A is a tape bearing surface view taken from Line 2A of FIG. 2.

FIG. 2B is a detailed view taken from Circle 2B of FIG. 2A.

FIG. 2C is a detailed view of a partial tape bearing surface of a pairof modules.

FIG. 2D is a schematic diagram of the bridging effect that can occur tomagnetic heads.

FIG. 2E is a schematic diagram showing an overetching effect that canresult from plasma etching on thin film regions.

FIG. 3A is a schematic diagram of ion milling at a first angle on a thinfilm region according to one embodiment.

FIG. 3B is a schematic diagram of ion milling at a second angle on athin film region according to one embodiment.

FIG. 3C is a schematic diagram of the result of ion milling at a firstand second angle on a thin film region according to one embodiment.

FIG. 3D is a schematic diagram of a thin film region after ion millingat a first and second angle including a protective coating according toone embodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

A method according to one general embodiment includes ion milling at afirst angle of greater than about 25 degrees from normal relative to amedia facing side of a thin film region of a magnetic head or componentthereof for recessing the thin film region at about a constant rate forfilms of interest of the thin film region, planes of deposition of thefilms being oriented about perpendicular to the media facing side; andion milling or plasma sputtering at a second angle of less than about 25degrees from normal relative to the media facing side of the thin filmregion for recessing magnetic films therein faster than insulating filmstherein, the second angle being smaller than the first angle.

A method according to another general embodiment includes ion milling ata first angle of between about 25 degrees and about 70 degrees fromnormal relative to a media facing side of a thin film region of amagnetic head or component thereof positioned between a substrate and aclosure for recessing the thin film region at about a constant rate forall films of the thin film region, planes of deposition of the filmsbeing oriented about perpendicular to the media facing side; and ionmilling or plasma sputtering at a second angle of between about 0 andabout 25 degrees from normal relative to the media facing side of thethin film region for recessing magnetic films therein faster thaninsulating films therein.

A structure according to one general embodiment includes a substratehaving a media facing side; and a thin film stack formed on thesubstrate, the thin film stack including magnetic films and insulatingfilms, wherein the thin film stack is recessed from a plane extendingalong the media facing side of the substrate, wherein the magnetic filmsare recessed more than the insulating films, wherein the magnetic filmseach have a substantially flat media facing surface, wherein theinsulating films each have a substantially flat media facing surface.

FIG. 1 illustrates a simplified tape drive 100 of a tape-based datastorage system, which may be employed in the context of the presentinvention. While one specific implementation of a tape drive is shown inFIG. 1, it should be noted that the embodiments described herein may beimplemented in the context of any type of tape drive system.

As shown, a tape supply cartridge 120 and a take-up reel 121 areprovided to support a tape 122. One or more of the reels may form partof a removable cassette and are not necessarily part of the system 100.The tape drive, such as that illustrated in FIG. 1, may further includedrive motor(s) to drive the tape supply cartridge 120 and the take-upreel 121 to move the tape 122 over a tape head 126 of any type.

Guides 125 guide the tape 122 across the tape head 126. Such tape head126 is in turn coupled to a controller assembly 128 via a cable 130. Thecontroller 128 typically controls head functions such as servofollowing, writing, reading, etc. The cable 130 may include read/writecircuits to transmit data to the head 126 to be recorded on the tape 122and to receive data read by the head 126 from the tape 122. An actuator132 controls position of the head 126 relative to the tape 122.

An interface may also be provided for communication between the tapedrive and a host (integral or external) to send and receive the data andfor controlling the operation of the tape drive and communicating thestatus of the tape drive to the host, all as will be understood by thoseof skill in the art.

By way of example, FIG. 2 illustrates a side view of a flat-lapped,bi-directional, two-module magnetic tape head 200 which may beimplemented in the context of the present invention. As shown, the headincludes a pair of bases 202, each equipped with a module 204, and fixedat a small angle α with respect to each other. The bases are typically“U-beams” that are adhesively coupled together. Each module 204 includesa substrate 204A and a closure 204B with a gap 206 comprising readersand/or writers situated therebetween. In use, a tape 208 is moved overthe modules 204 along a media (tape) bearing surface 209 in the mannershown for reading and writing data on the tape 208 using the readers andwriters. The wrap angle θ of the tape 208 at edges going onto andexiting the flat media support surfaces 209 are usually between ⅛ degreeand 4½ degrees.

The substrates 204A are typically constructed of a wear resistantmaterial, such as a ceramic. The closures 204B made of the same orsimilar ceramic as the substrates 204A.

The readers and writers may be arranged in a piggyback configuration.The readers and writers may also be arranged in an interleavedconfiguration. Alternatively, each array of channels may be readers orwriters only. Any of these arrays may contain one or more servo readers.

FIG. 2A illustrates the tape bearing surface 209 of one of the modules204 taken from Line 2A of FIG. 2. A representative tape 208 is shown indashed lines. The module 204 is preferably long enough to be able tosupport the tape as the head steps between data bands.

In this example, the tape 208 includes 4-22 data bands, e.g., with 16data bands and 17 servo tracks 210, as shown in FIG. 2A on a one-halfinch wide tape 208. The data bands are defined between servo tracks 210.Each data band may include a number of data tracks, for example 96 datatracks (not shown). During read/write operations, the elements 206 arepositioned within one of the data bands. Outer readers, sometimes calledservo readers, read the servo tracks 210. The servo signals are in turnused to keep the elements 206 aligned with a particular track during theread/write operations.

FIG. 2B depicts a plurality of read and/or write elements 206 formed ina gap 218 on the module 204 in Circle 2B of FIG. 2A. As shown, the arrayof elements 206 includes, for example, 16 writers 214, 16 readers 216and two servo readers 212, though the number of elements may vary.Illustrative embodiments include 8, 16, 32, and 64 elements per array206. A preferred embodiment includes 32 readers per array and/or 32writers per array. This allows the tape to travel more slowly, therebyreducing speed-induced tracking and mechanical difficulties. While thereaders and writers may be arranged in a piggyback configuration asshown in FIG. 2B, the readers 216 and writers 214 may also be arrangedin an interleaved configuration. Alternatively, each array of elements206 may be readers or writers only, and the arrays may contain one ormore servo readers 212. As noted by considering FIGS. 2 and 2A-Btogether, each module 204 may include a complementary set of elements206 for such things as bi-directional reading and writing,read-while-write capability, backward compatibility, etc.

FIG. 2C shows a partial tape bearing surface view of complimentarymodules of a magnetic tape head 200 according to one embodiment. In thisembodiment, each module has a plurality of read/write (R/W) pairs in apiggyback configuration formed on a common substrate 204A and anoptional electrically insulative layer 236. The writers, exemplified bythe write head 214 and the readers, exemplified by the read head 216,are aligned parallel to a direction of travel of a tape mediumthereacross to form an R/W pair, exemplified by the R/W pair 222.

Several R/W pairs 222 may be present, such as 8, 16, 32 pairs, etc. TheR/W pairs 222 as shown are linearly aligned in a direction generallyperpendicular to a direction of tape travel thereacross. However, thepairs may also be aligned diagonally, etc. Servo readers 212 arepositioned on the outside of the array of R/W pairs, the function ofwhich is well known.

Generally, the magnetic tape medium moves in forward and reversedirections as indicated by arrow 220. The magnetic tape medium and headassembly 200 operate in a transducing relationship in the mannerwell-known in the art. The piggybacked MR head assembly 200 includes twothin-film modules 224 and 226 of generally identical construction.

Modules 224 and 226 are joined together with a space present betweenclosures 204B thereof (partially shown) to form a single physical unitto provide read-while-write capability by activating the writer of theleading module and reader of the trailing module aligned with the writerof the leading module parallel to the direction of tape travel relativethereto. When a module 224, 226 of a piggyback head 200 is constructed,layers are formed in the gap 218 created above an electricallyconductive substrate 204A (partially shown), e.g., of AlTiC, ingenerally the following order for the R/W pairs 222: an insulating layer236, a first shield 232 typically of an iron alloy such as NiFe(permalloy), CZT or Al—Fe—Si (Sendust), a sensor 234 for sensing a datatrack on a magnetic medium, a second shield 238 typically of anickel-iron alloy (e.g., 80/20 Permalloy), first and second writer poletips 228, 230, and a coil (not shown).

The first and second writer poles 228, 230 may be fabricated from highmagnetic moment materials such as 45/55 NiFe. Note that these materialsare provided by way of example only, and other materials may be used.Additional layers such as insulation between the shields and/or poletips and an insulation layer surrounding the sensor may be present.Illustrative materials for the insulation include alumina and otheroxides, insulative polymers, etc.

Now referring to FIG. 2D, a common problem associated with magnetic readheads is bridging where portions of materials form surface bridgesbetween the read sensor films and the shields. In FIG. 2D, this effectis shown in relation to either poles or shields 244, which are typicallyseparated by an insulator 242 of some type. Motion of the tape 208across the surface of the head may assist in formation of conductivebridges, and if enough material bridges across the surface of theinsulator 242, an electrical connection 240 may form between the readsensor and the shields 244, which can result in shorting and headfailure, rendering the device inoperable. In order to correct thisproblem, it is generally preferable to have the shields or poles 244recessed to a height less than the insulators 242, thereby rendering itless likely for material to form an electrical connection 240 across theinsulators 242.

Bridging may involve, for example, migration of metallic films on thehead surface or may involve more complex processes such aselectrochemical formation or media deposition or interactions.

Referring to FIG. 2E, a method for minimizing the bridging effect is torecess the entire thin film region 248 of a magnetic head through plasmaetching 246. However, argon plasma etching 246 may be overly selectiveof the poles and shield portions of the thin film region 248, resultingin a loss of signal amplitude, symmetry, or resolution. To overcome thisproblem, a more uniform etching or milling method is needed forproducing a recessed thin film region 248 without overetching the polesand shields.

Now referring to FIGS. 3A-3D, a method according to one embodiment isshown. In FIG. 3A, a substrate 204A and a closure 204B may form portionsof an air bearing surface (ABS) or a tape bearing surface (TBS), and mayfurther define a thin film region 300 which may include multiple thinfilms which may reside in a gap, such as gap 206 shown in FIG. 2B. Forillustrative purposes, several of these thin films are identified inFIGS. 3A-3D and the thin films are shown in relation to a gap between asubstrate 204A and a closure 204B. Moving from the substrate 204A towardthe closure 204B, a first thin film may be the undercoat insulation 306,then a first shield 308 which should be insulated from a sensorstructure 312 by any number of thin films 310, 314, including at leastone insulator. Next, an insulator 318 may separate the second shield 316from a first pole 320. Next, another insulator 322, often forming thewrite transducer gap, may separate the first pole 320 from a second pole324 in the gap region. An overcoat insulator 326 may be next, followedby a bondline 328 near the closure 204B. There may also be other thinfilms and the overall design and ordering of these thin films is forillustrative purposes only, and in no way should limit the invention,nor should the inclusion of the substrate 204A and closure 204B in thisdescription.

Referring to FIG. 3B, a method, according to one embodiment, comprisesion milling the structure shown in FIG. 3A at a first angle φ of greaterthan about 25° from normal 330 relative to a media facing side 332,sometimes referred to as the air bearing surface (ABS) or tape bearingsurface (TBS), of a thin film region 300 of a magnetic head or componentthereof for recessing the thin film region 300 at about a constant ratefor the films of interest (e.g., the magnetic and transducing films(including films that may be both magnetic and transducing) such as thewrite poles 320, 324 and magnetic and possibly other portions of thesensor 312; the shields 308, 316; and insulating layers adjacent to themagnetic and transducing films) of the thin film region 300, planes ofdeposition of the films being oriented about perpendicular to the mediafacing side 332. Note that some films may etch at a different rate thanthe films of interest. For example, the leads (not shown) tend to etchmore slowly than other layers when milled at the first angle. Note alsothat the structure being milled is typically rotated relative to the ionsource, or vice versa, during the milling.

The methodology described herein may also be applied to heads havingfilms at an angle of less than 90° to the tape bearing surface.

In particularly preferred embodiments, the first angle φ may be greaterthan about 50°, between about 50° and about 70°, ideally about 60°. Ionmilling at about 60° is relatively non-selective, and thus most gapmaterials tend to etch at approximately the same rate.

With continued reference to FIG. 3B, the result of ion milling at thefirst angle φ according to one embodiment is shown, as the thin filmregion 300 has been recessed from the media facing side 332 by adistance β. The distance β may be adjusted depending on the particulareffect desired by the method. Note that some of the metallic layers,e.g., the first shield 308, portions of the read sensor 312, secondshield 316, first pole 320, and/or second pole 324 may protrude slightlyfrom the overall plane of the media facing surface.

Referring to FIG. 3C, the method may further comprise ion milling orplasma sputtering at a second angle ψ of less than about 25° (andpreferably greater than 0°) from normal 330 relative to the media facingside 332 of the thin film region 300 for recessing magnetic films, suchas iron-containing films, and potentially other metallicalloy-containing films, therein faster than insulating films therein.For example, this ion milling at a second angle ψ could be used torecess the first shield 308, read sensor 312, second shield 316, firstpole 320, and/or second pole 324 faster than the insulating layers(e.g., 318, 322, etc.) therebetween are recessed.

In other embodiments, the second angle ψ may be between about 0° andabout 25°, preferably about 5° to about 15°, ideally about 15°.

With continued reference to FIG. 3C, the result of ion milling at thesecond angle ψ according to one embodiment is shown, as the magneticfilms have been recessed by a distance ε more than the insulatinglayers. The distance ε may be adjusted depending on the desired effectof the method. The magnetic films were recessed faster than theinsulating films, resulting in more material being removed in the sameamount of exposure time to the ion milling. By leaving the insulatingfilms exposed above the upper surface of the magnetic films, conductivebridging between the films should be substantially reduced or eliminatedsince the insulating layers should make it more difficult for materialfrom recessed films to form electrical connections between the recessedfilms.

Now referring to FIG. 3D, an optional step according to one embodimentis shown, where a protective coating 334 may be formed above the mediafacing side 332 of the thin film region 300. This protective coating 334may also be applied to the media facing side 332 of the substrate 204Aand closure 204B. In addition, this protective coating 334 above thethin film region 300 may not be so thick as to extend to a planeextending along a media facing side 332 of a substrate on which thefilms are formed, as shown in FIG. 3D. In another approach, thisprotective coating 334 may extend to a plane extending along a mediafacing side 332 of a substrate on which the films are formed. Forexample, the depth of the protective coating 334 may be such that thecoating fills the distance between the upper surface of the thin filmregion 300 and the upper surface of the substrate 204A and closure 204B,or to an additional height as determined by the protective coating 334thickness on the upper surface of the substrate 204A and closure 204B.

In other embodiments, at least some of the metallic films may form writepoles or reader shields or both write poles and reader shields.

In one embodiment, the ion milling at the first angle φ may be performedbefore the ion milling and/or sputtering at the second angle ψ. Further,the ion milling and/or sputtering may be continuously performed as theion milling angle is transitioned from the first angle φ to the secondangle ψ.

In another embodiment, the ion milling and/or sputtering at the secondangle ψ may be performed before the ion milling at the first angle φ.Further, the ion milling and/or sputtering may be continuously performedas the ion milling angle is transitioned from the second angle φ to thefirst angle ψ.

Moreover, a combination of the foregoing continuous milling and/orsputtering may be performed such that the milling and/or sputtering isperformed in both forward and backward angular directions. Further,continuous loops of milling between the first and second angles may beperformed, thereby milling or sputtering continuously and repeatedly,back and forth, between the first and second angles.

In other approaches, the milling or sputtering is performed inalternating fashion in the first and second angles. The number ofrepetitions, and the processing time at each angle can be selected toachieve the desired profile.

In further approaches, milling and/or sputtering may be performed atadditional angles, e.g., a third angle between the first and secondangles.

In various approaches, the target may be stationary, rotating, or acombination of both.

Keeping in mind that definitions from above may apply to thedescriptions below, and with continued reference to FIGS. 3A-3D, anothermethod, according to one embodiment, comprises ion milling at a firstangle φ of between about 50° and about 70°from normal 330 relative to amedia facing side 332 of a thin film region 300 of a magnetic head orcomponent thereof positioned between a substrate 204A and a closure 204Bfor recessing the thin film region 300 at about a constant rate for thefilms of interest of the thin film region 300, planes of deposition ofthe films being oriented about perpendicular to the media facing side332; and ion milling at a second angle ψ of between about 0° and about25° from normal 330 relative to the media facing side 332 of the thinfilm region 300 for recessing metallic films (e.g., 308, 316, 320, etc.)therein faster than insulating films (e.g., 306, 318, 326, etc.)therein.

With reference to FIG. 3D, a structure, according to one embodiment, maycomprise a substrate 204A having a media facing side 332 (which issometimes called an ABS or TBS); and a thin film stack 300 formed on thesubstrate 204A, the thin film stack 300 including magnetic and otheralloy-containing films (e.g., 308, 316, 320, etc.) and insulating films(e.g., 306, 318, 326, etc.), wherein the thin film stack 300 is recessedfrom a plane extending along the media facing side 332 of the substrate204A (e.g., by a distance β′), wherein the magnetic films are recessedmore than the insulating films (e.g., by a distance ε), wherein themagnetic films each have a substantially flat media facing surface,wherein the insulating films each have a substantially flat media facingsurface.

In one embodiment, milling atoms are not embedded in the magnetic ortransducing films other than those present immediately after formationof the thin film stack 300, as well as possible oxidation or corrosionproducts.

It will be clear that the various features of the foregoingmethodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of a preferred embodiment shouldnot be limited by any of the above-described exemplary embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

1. A structure, comprising: a substrate having a media facing side; anda thin film stack formed on the substrate, the thin film stack includingmagnetic films and insulating films, wherein the thin film stack isrecessed from a plane extending along the media facing side of thesubstrate, wherein the magnetic films are recessed more than theinsulating films, wherein the magnetic films each have a substantiallyflat media facing surface, wherein the insulating films each have asubstantially flat media facing surface.
 2. The structure of claim 1,wherein milling atoms are not embedded in the magnetic or transducingfilms other than those present immediately after formation of the thinfilm stack.
 3. The structure of claim 1, further comprising a closurecoupled to the thin film stack opposite the substrate, the substrate andclosure forming portions of a tape bearing surface.
 4. The structure ofclaim 1, further comprising a protective coating over a media facingside of the thin film stack.
 5. A data storage system, comprising: amagnetic head having the structure as recited in claim 1; a drivemechanism for passing a magnetic medium over the magnetic head; and acontroller electrically coupled to the magnetic head.